Excess NaCl Research Articles

Overexpression of spinach non-symbiotic hemoglobin in Arabidopsis resulted in decreased NO content and lowered nitrate and other abiotic stresses tolerance.

A class 1 non-symbiotic hemoglobin family gene, SoHb, was isolated from spinach. qRT-PCR showed that SoHb was induced by excess nitrate, polyethylene glycol, NaCl, H2O2, and salicylic acid. Besides, SoHb was strongly induced by application of nitric oxide (NO) donor, while was suppressed by NO scavenger, nitrate reductase inhibitor, and nitric oxide synthase inhibitor. Overexpression of SoHb in Arabidopsis resulted in decreased NO level and sensitivity to nitrate stress, as shown by reduced root length, fresh weight, the maximum photosystem II quantum ratio of variable to maximum fluorescence (Fv/Fm), and higher malondialdehyde contents. The activities and gene transcription of superoxide dioxidase, and catalase decreased under nitrate stress. Expression levels of RD22, RD29A, DREB2A, and P5CS1 decreased after nitrate treatment in SoHb-overexpressing plants, while increased in the WT plants. Moreover, SoHb-overexpressing plants showed decreased tolerance to NaCl and osmotic stress. In addition, the SoHb-overexpression lines showed earlier flower by regulating the expression of SOC, GI and FLC genes. Our results indicated that the decreasing NO content in Arabidopsis by overexpressing SoHb might be responsible for lowered tolerance to nitrate and other abiotic stresses.

High Salt Activates Human Monocytes and Promotes their Conversion into Dendritic Cells via Formation of Immunogenic Isoketal‐adducts

High blood pressure is a major modifiable risk factor for cardiovascular disease (CVD) which is the leading cause of death worldwide. Excessive salt intake and inflammation are implicated in the genesis of hypertension. It has recently become evident that sodium accumulates in the interstitial space and can promote inflammation through poorly defined mechanisms. We recently published a new pathway in which increased oxidative stress in dendritic cells (DCs) leads to formation of isoketal‐modified proteins which act as neo‐antigens to activate T cells. We hypothesized that increasing sodium chloride (NaCl) in excess of the physiological interstitial space concentrations activates antigen presenting cells via formation of immunogenic isoketals. We exposed monocytes from human volunteers to normal physiological NaCl (150 mM/L), elevated NaCl concentrations (190 mM/L), or an equiosmoloar concentration of mannitol. We found that exposure of human monocytes to high salt, but not mannitol, caused a 2‐fold increase in formation of isoketal‐modified proteins. This was associated with an increase in activation marker CD86 (466 ± 192 normal salt vs 596 ± 324 high salt) and production of inflammatory cytokines IL‐6, IL‐β and TNF‐α. Interestingly, these cells expressed surface markers indicative of transformation to DCs, as evidenced by their acquisition of surface marker CD83. In additional immunofluorescence studies, we found that monocytes exposed to high salt for 7 days acquire a DC like morphology. Moreover, using flow cytometry, we confirmed that high salt exposure causes these cells to lose the monocyte marker CD14, and gain the DC marker CD209. When co‐cultured with T cells from the same patients, these cells drive T cell proliferation. Scavenging of isoketals during high salt exposure prevented conversion of monocytes into DCs and their ability to drive T cell proliferation. Thus, we have defined a novel pathway whereby high NaCl concentrations lead to transformation of monocytes to DCs due to increased formation of immunogenic isoketals. These observations provide insight into how elevated sodium environments lead to an inflammatory state.Support or Funding InformationThis work is supported by National Institutes of Health grants R01HL039006, P01HL058000, P01HL095070, P01GM015431, R01HL108701, R01HL105294, VITA award HHSN268201400010C and the Strategically Focused Research Network Award from the American Heart Association.

Hyperosmolar sodium chloride is toxic to cultured neurons and causes reduction of glucose metabolism and ATP levels, an increase in glutamate uptake, and a reduction in cytosolic calcium

Elevation of serum sodium, hypernatremia, which may occur during dehydration or treatment with sodium chloride, may cause brain dysfunction and damage, but toxic mechanisms are poorly understood. We found that exposure to excess NaCl, 10–100mmol/L, for 20h caused cell death in cultured cerebellar granule cells (neurons). Toxicity was due to Na+, since substituting excess Na+ with choline reduced cell death to control levels, whereas gluconate instead of excess Cl− did not. Prior to cell death from hyperosmolar NaCl, glucose consumption and lactate formation were reduced, and intracellular aspartate levels were elevated, consistent with reduced glycolysis or glucose uptake. Concomitantly, the level of ATP became reduced. Pyruvate, 10mmol/L, reduced NaCl-induced cell death. The extracellular levels of glutamate, taurine, and GABA were concentration-dependently reduced by excess NaCl; high-affinity glutamate uptake increased. High extracellular [Na+] caused reduction in intracellular free [Ca2+], but a similar effect was seen with mannitol, which was not neurotoxic. We suggest that inhibition of glucose metabolism with ensuing loss of ATP is a neurotoxic mechanism of hyperosmolar sodium, whereas increased uptake of extracellular neuroactive amino acids and reduced intracellular [Ca2+] may, if they occur in vivo, contribute to the cerebral dysfunction and delirium described in hypernatremia.

Carbothermal reduction of beach sand to graphite silicate and silicon carbide

Silicon carbide has very specific application scope in the field of energy storage device fabrication. In this paper we have attempted a cost effective, energy saving single step method to fabricate graphite silicate (SiO2C) and silicon carbide (SiC) from beach sand. Carbothermal reduction of sand by microwave heating was found successful to produce SiO2C/SiC at 800°C. Nano sheets of graphite silicate and nanorods of SiC were formed at 800°C when heated for 60 minutes. When the heating time was increased to 120 min, formation of such nanosheets was abundant. But when the time was further increased to 180 min, agglomeration as well as compacting of the nano sheets was seen. But microwave heating to 480 min at 800°C showed completely sintered irregular particles of SiO2C/SiC in the product. Experiments were conducted using a mixture of carbon, sand and highly excess quantity of NaCl. The exorbitant amount of heat generated during the carbothermal reduction of sand was allowed to dissipate in the excess NaCl and the sintering effect was minimized. In this reaction, formation of pure SiC nano rods/thin long sheets was seen. The temperature suitable for preparation of graphite silicate/SiC was found to be 800°C with a soaking time of 60 to 120 min.

How strong are strong poly(sulfonic acids)? An example of the poly(2-acrylamido-2-methyl-1-propanesulfonic acid)

Despite the significant interest in poly(sulfonic acids) as proton conductors and acid catalysts, their dissociation behavior is poorly studied. The influence of the polyelectrolyte effect on the dissociation of the strong poly(acid) is frequently neglected. Moreover, the decrease in distance between the sulfonic groups is thought to enhance the acid strength or charge carrier concentration. Using simple and reliable methods (pH measurements and potentiometric titration), it is demonstrated that a strong poly(sulfonic acid) such as poly(2-acrylamido-2-methyl-1-propanesulfonic acid) displays a “limited” (predicted by the Manning-Oosawa theory) degree of dissociation in a salt-free solution and “maximal” degree of dissociation equivalent to the monomer analog in the presence of NaCl excess.

Abstract 11587: Excessive NaCl Intake Aggravates Aortic Dissection Through IL-17 Pathway

Excessive NaCl intake is an established risk factor of cardiovascular events, although the molecular mechanism has not been fully understood. Aortic dissection (AD) is one of the fatal cardiovascular events, in which proinflammatory response is proposed to be important. In this study, we investigated the effect of excessive NaCl intake on a mouse AD model that was induced by continuous infusion of beta-aminopropionitrile (BAPN), a collagen/elastin crosslink inhibitor, and angiotensin II (AngII). BAPN+AngII caused thoracic and suprarenal AD in most of the mice within 2 weeks. Excessive NaCl intake was achieved by giving 1% NaCl as drinking water (Hi-Na) 1 week prior to and during the BAPN+AngII infusion. The lesion length of AD was significantly longer in Hi-Na group than in normal water group, even though systolic blood pressure or pulse rate showed no significant changes. Because recent studies have demonstrated that excessive NaCl activates TH17/IL-17 pathway that is central to the inflammatory response, we examined the involvement of IL-17 in AD using IL-17 knockout mice (IL17-KO). Deletion of IL-17 gene abolished the exacerbating effect of NaCl on the severity of AD. Transcriptome analysis of aortae before AD onset showed that strong induction of proinflammatory genes and suppression of extracellular matrix (ECM) genes precede the AD development in this model. Although IL-17 is central to inflammatory response in general, alteration of inflammatory response was not prominent in IL17-KO aorta. Instead, genes of ECM was upregulated in IL17-KO at the baseline. With BAPN+AngII and excessive NaCl intake, expression of ECM genes were higher in IL17-KO compared to wild type aorta. Picrosirius red staining showed that the amount of medial collagen fibers, the major ECM to support the physical strength of aorta, was increased in IL17-KO compared to wild type mice without NaCl overload or BAPN+AngII administration. These data uncovered the unexpected role of IL-17 to suppress the ECM deposition in aorta. Because ECM is essential to maintain the physical strength of aortic walls, the increase of ECM would explains why IL17-KO aorta is protected from dissection. NaCl intake and IL-17 may represent important therapeutic targets for AD.

High concentrations of NaCl induce cell swelling leading to senescence in human cells

Cell swelling and retardation in DNA replication are always observed in senescent cells. When DNA replication is slowed down with RNA and protein syntheses unchanged in proliferating cells, it causes a phenomenon known as unbalanced growth. The purpose of this study is to assess the role of cell swelling in unbalanced growth in terms of senescence and investigate the mechanism underlying this phenomenon. We tried to induce cell swelling with minimum damage to cells in this study. We perturbed the osmoregulatory functions to induce cell swelling under hypotonic and hypertonic conditions in normal human fibroblasts. Addition of excess NaCl was found to induce significant cell and nuclear swelling in dose- and time-dependent manners. Excess NaCl immediately retarded DNA replication, accumulated cells at G1 phase of the cell cycle, and eventually deprived division potential of the cells. Such cells showed typical senescent cell shape followed by expression of the typical senescence-associated genes. Excess NaCl also activated ERK1/2, p38, and JNK of the mitogen activated protein kinase family. Addition of U0126, an inhibitor of ERK1/2, prevented appearance of senescent features induced by excess NaCl. These results suggest that hypertonic conditions induce cell swelling due to unbalanced growth, thereby leading to cellular senescence.

Synthesis of Uniform, Monodisperse, Sophorolipid Twisted Ribbons.

Control over size monodispersity in chiral self-assembled systems is important for potential applications like templating, tissue engineering or enantioselective chromatography, just to cite a few examples. In this context, it was reported that the saturated form of sophorolipids (SL), a bioderived glycolipid, are able to form self-assembled twisted ribbons in water at neutral pH. Here, we show the possibility to control their size dispersion, generally between 10 and 40 nm after synthesis to a value of 13.5±1.5 nm, by a simple dialysis step eliminating the excess of NaCl. We use transmission electron microscopy under cryogenic conditions (cryo-TEM) combined with small angle neutron scattering (SANS) to characterize the ribbon dispersion both visually and statistically. Two negative controls show the importance of salt in the aggregation process of the ribbons.

Guanylin activates Cl(-) secretion into the lumen of seawater eel intestine via apical Cl(-) channel under simulated in vivo conditions.

Guanylin (GN) action on seawater eel intestine was examined under simulated in vivo conditions, where isotonic luminal fluid has low NaCl and high MgSO4 (MgSO4 Ringer). In Ussing chamber, MgSO4 Ringer induced serosa-negative potential difference (PD) even after bumetanide treatment, which is due to the higher paracellular Na(+) permeability over Cl(-), as confirmed by the replacement by MgCl2 (no Cl(-) gradient) or Na2SO4 Ringer (no Na(+) gradient). Luminal GN reversed serosa-negative PD, probably by enhancing Cl(-) secretion into the lumen, as the GN effect was blocked by apical Cl(-) channel blockers [diphenylamine-2-carboxylic acid (DPC), 5-nitro-2-(3-phenylpropylamino) benzoic acid, glibenclamide but not cystic fibrosis transmembrane regulator (CFTR)inh-172] or replacement of luminal fluid by MgCl2 Ringer. The blockers' effect was undetectable when normal Ringer was on both sides. In the sac preparation, NaCl secretion occurred into the lumen (Na(+) > Cl(-)), and GN further enhanced Cl(-) secretion (Cl(-) > Na(+)), resulting in water secretion. These GN effects were also blocked by DPC. Quantitative analyses showed that isotonic NaCl is absorbed when luminal fluid is normal Ringer, but, when luminal fluid is MgSO4 Ringer, hypertonic NaCl, almost equivalent to seawater, is secreted into the lumen after GN. These results indicate that GN stimulates the secretion of hypertonic NaCl into the lumen of seawater eel intestine, like rectal gland of marine elasmobranchs, to get rid of excess NaCl although marine teleost intestine is thought to have only absorptive-type cells with a unique Na-K-Cl cotransport system. The secreted NaCl may activate the cotransport system and further help absorb water in the final segment of seawater eel intestine.

Nb3(µ3-Cl)(µ-Cl)3(CH3CN)9] (GaCl4)4, A Discrete, Seven Valence Electron Triniobium Cluster Derivative of Nb3Cl8

Solid state reduction of NbCl5, with excess NaCl, by Ga2Cl4 under lower-temperature (175°) kinetic control yields a brown powder from which the green, incomplete cubane cluster compound [Nb3(µ3-Cl)(µ-Cl)3(NCCH3)9]4+, with GaCl4 − anions, can be extracted by acetonitrile in 51 % isolated yield. This seven valence electron discrete cluster is a moderately-soluble coordination complex of the known, seven electron, extended structure (Nb3Cl8)x. The solid state structure consists of a triangular cluster with one face-capping µ3-Cl, three edge-bridging µ-Cl ligands on the opposite face, and three terminal N-bonded CH3CN ligands per Nb. The average Nb–Nb, Nb–(µ3-Cl), and Nb–(µ-Cl) distances for one of the four independent cluster cores in the unit cell are 2.811[1] A, 2.438[9] A, and 2.427[3] A, respectively, and the average Nb–(µ-Cl)–Nb angle is 70.8[1]°. These values are compared to those of other discrete triniobium clusters and triniobium chloride extended structures with the Nb3(µ3-X)(µ-X)3XnL9−n incomplete metallacubane structure.

Nickel Sulfide Concentrate Processing Using Low-Temperature Roasting with Sodium Chloride

A method is proposed for processing nickel sulfide concentrates based on low-temperature roasting with sodium chloride. In the course of research, the dependence of valuable component extraction on excess sodium chloride and roasting temperature and duration is determined, and also cinder water and sulphuric acid leaching regimes are optimized. Optimum results are achieved with the following roasting regimes: temperature 400°C, duration 1.5 h, and excess NaCl 50–200% of concentrate weight. A production scheme is proven on a laboratory scale with subsequent two-stage water and sulphuric acid leaching with calculation of the material balance for nickel, copper, cobalt, and iron. Complete extraction into solution is, %: Ni 95, Cu 99, Co 96.

Salt tolerance in Populus: Significance of stress signaling networks, mycorrhization, and soil amendments for cellular and whole-plant nutrition

Abiotic stress tolerance is important for trees that have to withstand unfavorable environmental condi- tions for longer periods of time than crop plants with short life cycles. Salinity (excess NaCl) is a common abiotic stress factor that limits tree growth by interfering with major physiological functions, disrupting ion homeostasis and diminishing nutrient uptake in plant cells. Here we review the salt signaling cascades that control cellular K+ and Ca2+ homeostasis, which are also affected by reactive oxygen species signaling, extracellular ATP signaling, and crosstalk among pathways in the salt-resistant model tree Populus euphratica. We discuss the uptake and transport of essential nutrients, especially N (NH4+, NO3−), P, S, K+, Ca2+, and Mg2+, that constitute the whole-plant response to salinity and its impact on tree physiology. To date, transgenic approaches have achieved only limited enhancements of the salinity tolerance of salt-sensitive Populus. Therefore, we recommend the use of alternative biotechnological tools such as mycorrhization and polymer amendment. Ectomycorrhizal fungi have beneficial effects for their hosts under salt stress because they exclude Na+ and improve nutrient conditions, e.g. by increasing N, P, Ca2+, and K+ levels. Applying hydrogel to the soil improves poplar growth under salinity, an effect attributed to both increased K+ and Ca2+ uptake as well as the reduced accumulation of salt ions.

ChemInform Abstract: Na2Y3Cl3[TeO3]4: Synthesis, Crystal Structure and Spectroscopic Properties of the Bulk Material and Its Luminescent Eu3+‐Doped Samples.

AbstractColorless single crystals of the title compound are prepared by solid state reaction of Y2O3 and TeO2 in a molar ratio of 3:8 with an excess of NaCl as flux and reactant (silica ampule, Ar, 775 °C, 5 d).

Effect of Salinity on the Survival, Ions and Urea Modulation in Red-eared Slider (Trachemys scripta elegans)

To understand the tolerance to salinity and osmoregulation of the introduced Trachemys scripta elegans, the salinity stress of four groups (salinity 5 parts per thousand, 15 parts per thousand, 25 parts per thousand and control group) were conducted. Inorganic ions, osmotic pressure, glucose and aldosterone of blood and urine in T. s. elegans (BW: 125.60 +/- 19.84 g) were analyzed at 30 d, 60 d and 90 d stress. The results showed that: 1) inorganic ions concentration of blood and urine increased with ambient salinity, which indicated that high influx of ions was combined with higher outflow when exposed to saline water in T. s. elegans. However, blood aldosterone decreased with increasing salinity, which indicated that an increased sodium intake resulting in a diminished aldosterone production. However, with elapsed time, inorganic ions in urine decreased, which indicated that inorganic ions in blood would be accumulated, and Na+ and Cl- in the plasma inevitably build up to harmful levels, at last death was happening when T. s. elegans was exposed to salinity 25 during 90 d salinity stress; 2) blood osmotic pressure increased as ambient salinity increased, it would reach 400 mOsm/kg in the group of salinity 25, which was about 1.5 fold of the control group. Higher blood osmotic pressure was due to both higher blood ions and urea concentrations. There may be another mechanism to avoid an excess of NaCl together with an important loss of water using one of the end-products of nitrogen metabolism; 3) blood glucose in each group except the group of salinity 5 decreased with time elapsed and with salinity increased. Therefore, we can conclude that T. s. elegans is an osmoregulator that limits the entry of Na+ and Cl-, but can also tolerate certain degrees of increases in plasma Na+ and Cl-. When ambient salinity was lower than 15 parts per thousand, T. s. elegans can increase blood osmotic pressure by balancing the entry of NaCl with the secretion of aldosterone decreased, and by accumulating blood urea for osmoregulation effectors, and survive for at least three months. These results could provide theoretical basis for salinity tolerance and the invasion on physiological mechanism for T. s. elegans.

THU0051 Sodium Chloride Drives Lupus Nephritis via the Induction of Pathogenic SGK1 Pathways

BackgroundEvidences have suggested excess NaCl content in diet is a potential environmental risk factor for autoimmune diseases. Na+ transport and NaCl homeostasis are controlled by the serum and glucocorticoid- inducible...

PH-responsive micelles and vesicles formed from a water-soluble schizophrenic diblock copolymer

A pH-responsive diblock polymer (pDEA-b-pAaH) composed of poly(N,N-diethylaminoethyl methacrylate) (pDEA) and poly(6-acrylamidohexanoic acid) (pAaH) was synthesized via reversible addition-fragmentation chain transfer (RAFT) controlled/living radical polymerization and characterized by NMR. pDEA-b-pAaH in water and salt solution self-assembled to schizophrenic micelles in acidic and basic conditions. NMR, light scattering, TEM, and fluorescence measurements provided clear evidence of core–shell micelles and inverted micelles under acidic and basic pH conditions. The micelle size was determined by dynamic light scattering (DLS) measurement at different pH values. pDEA-b-pAaH does not dissolve in water at around pH 6, because the anionic pAaH and cationic pDEA blocks were subject to electrostatic interactions; however, the precipitate formed in pure water at pH 6 dissolved in 1.1M NaCl because the electrostatic interactions were screened by the large excess of NaCl. When pDEA-b-pAaH in 1.1M NaCl aqueous solution was dialyzed against pure water to remove NaCl, the polymer formed a vesicle structure that could incorporate water-soluble polymer guest molecules into the interior water phase.

Phosphorylation dynamics of membrane proteins from Arabidopsis roots submitted to salt stress

An excess of NaCl in the soil is detrimental for plant growth. It interferes with mineral nutrition and water uptake and leads to accumulation of toxic ions in the plant. Understanding the response of roots to NaCl stress may facilitate the development of crops with increased tolerance to this and other stresses. Since controls achieved at the posttranslational level are of critical importance for regulating protein function, the present work used a robust label-free quantitative proteomic methodology to quantify phosphorylation events that affect root membrane proteins in Arabidopsis, in response to short-term (up to 2 h) NaCl treatments. This work identified 302 proteotypic phosphopeptides including 77 novel phosphorylated sites. NaCl treatment significantly altered the abundance of 74 phosphopeptides, giving novel insights into the regulation of major classes of membrane proteins, including ATPases, sodium transporters, and aquaporins. The data provide a unique access to phosphorylation reprogramming of ionic equilibrium in plant cells under NaCl stress. The use of predictive bioinformatic tools for kinase motifs suggested that root membrane proteins are substrates of cAMP-dependent protein kinase, cGMP-dependent protein kinase, and protein kinase C families, also called AGC kinases, arguing for an important role of lipid signaling in abiotic stress responses. It also pointed to cross-talks between protein kinase families during NaCl stress.

Na2Y3Cl3[TeO3]4: Synthesis, Crystal Structure and Spectroscopic Properties of the Bulk Material and its Luminescent Eu3+-doped Samples

Colorless, platelet-shaped single crystals of Na2Y3Cl3[TeO3]4 were synthesized by a reaction of Y2O3 and TeO2 (molar ratio 3 : 8) in evacuated silica ampoules within five days at 775 °C with an excess of NaCl added as flux and reagent. The new quintenary compound crystallizes in the monoclinic space group C2/c with the lattice parameters a = 2380:69(14), b = 552:76(3), c = 1662:48(9) pm, β = 134:045(3)° and Z = 4. The crystal structure presents one of the rare oxotellurates(IV) containing isolated [TeO3]2− units, which could be verified by Raman spectroscopy. Doping with Eu3+ (3 mass-%) at the Y3+ sites in eightfold oxygen coordination leads to a strong orange-red luminescence of Na2Y3Cl3[TeO3]4:Eu3+ under UV excitation with a wavelength of λ = 254 nm. Beyond the electronic Eu3+ transitions of the 4 f 6 state, the fluorescence excitation spectrum shows an intense broad charge-transfer band resulting from both O2−→Eu3+ ligand-to-metal charge-transfer (LMCT) as well as electronic Eu3+ d→f and Te4+s→p transitions. The emission spectrum features the prominent f→f transitions of Eu3+-doped oxidic compounds. The optical band gaps of the undoped and doped samples were determined by diffuse reflectance spectroscopy revealing just minimal doping effects on the crystal structure. The optical band gaps could be assigned in the excitation spectrum in the charge-transfer broad-band region supporting the assumption of an inorganic antenna effect of the Te4+ cations.

Potassium fertiliser enhances the salt-tolerance of common bean (Phaseolus vulgaris L.)

SummarySodium chloride (NaCl) is the most abundant salt that contributes to soil salinity. The response of plants to excess NaCl is complex, involving changes in their morphology, physiology, and metabolism. Potassium (K) is not only an essential macronutrient for plant growth and productivity, but it is also a primary osmoticum for maintaining the low water potential of plant tissues. A pot experiment was conducted in the wire-house of the National Research Centre, Cairo, Egypt, during the 2010 – 2011 season, to examine the potential role of K fertiliser in alleviating the deleterious effects of NaCl-salinity on some physiological and biochemical traits of two recombinant inbred lines (RILs) of common bean (Phaseolus vulgaris L.; RIL 147 and RIL 115). The results showed that salinity levels of 25 mM (S1) and 50 mM NaCl (S2) caused significant decreases in the numbers of pods per plant, the fresh weight (FW) and dry weight (DW) of pods per plant, shoot DW per plant, as well as in the level of photosynthetic pigments, compared to plants irrigated with tap water (S0). A dose of 150 mg K2O kg–1 soil (K2) mitigated these harmful effects of salinity on common bean yield and on the content of photosynthetic pigments. Both salinity levels (S1 and S2) and treatment K2 caused significant increases in proline, free amino acid, and soluble carbohydrate concentrations, as well as peroxidase and polyphenol oxidase activities, relative to the corresponding control plants. In contrast, both RILs show a decrease in their phenolic compound concentrations due to salinity and/or the application of K2 compared to control plants (i.e., treatment S0K1; where K1 = 25 mg K2O kg–1 soil). The K+:Na+ ion ratio decreased significantly as the salinity level increased, and increased significantly under treatment K2. We conclude that treatment K2 mitigated the adverse effects of salinity (NaCl) through the effect of K+ ions enhancing the levels of photosynthetic pigments, anti-oxidant enzyme activities, osmoprotectant concentrations, and the K+:Na ion ratio, all of which were reflected in an improvement in plant performance.

Solution-Diffusion–Electro-Migration model and its uses for analysis of nanofiltration, pressure-retarded osmosis and forward osmosis in multi-ionic solutions

This work presents an analytical solution to the differential equations that govern the electrically coupled transport of three different ions through membrane barrier layers in which the Solution-Diffusion–Electro-Migration model applies. This model disregards convective coupling between the trans-membrane flows of ions and solvent and uses composition-independent single-ion permeances to quantify ion transfer through the membrane. The limited number of adjustable parameters should make their unambiguous determination feasible from a limited set of experimental data. The solution presented here enables rapid calculations that explore the effects of spontaneously arising electric fields on rejections in nanofiltration (NF), volume flows in pressure-retarded osmosis (PRO) through NF membranes, and NaCl rejections in forward osmosis (FO). For NF, ion flux simulations confirm that large differences in the permeances of mono and divalent ions, e.g. Mg2+ and Cl− or Na+ and SO42−, can lead to negative rejections or enhanced rejections of trace monovalent ions, depending on the ion charge. Calculations also show that rejection of divalent ions by NF membranes can lead to significant osmotic flow, even in the presence of some excess of NaCl. Osmotic flow first decreases and then increases as the NaCl concentration increases in a draw solution containing MgCl2 or Na2SO4. In FO using MgCl2 as a draw solution and NF membranes, modeling reveals 3- to 4-fold enhancements in NaCl rejection relative to a pressure-driven process under similar conditions. These results demonstrate the importance of modeling coupled ion transport when designing membrane-based ion separations.